Chihiro Shindou

Chihiro Shindou is the younger* twin sister of Kei Shindou and is one of the main heroines of Memories. At age 12 she was struck by an automobile, which resulted in the loss of her left eye and significant brain damage. Due to the accident she has a severe case of anterograde amnesia, where she cannot persist new memories beyond thirteen hours. She can perfectly recall the events before the accident. She currently lives in Otowa, Australia with her legal guardian, Yuu Himura, whom she knew before the accident as her 'big brother' (onii-chan), although they are not actually related.

Chihiro carries a diary with her in which she writes the events of that day so that she can recall them later. Ironically, she has a fantastic memory of anything that happened that is less than thirteen hours old.

Before the accident, she was outgoing and active like her twin sister Kei. After the accident she became quiet and reserved. She enjoys reading and has a dream of writing. She is a rotten cook (same as Kei).

Chihiro's love interest is Renji Asou, who has made a promise to help her achieve her dream of writing a novel. She writes in her diary about her growing affection for Renji, but because she does not clearly distinguish her feelings from actual events in her diary, she sometimes overreacts when she meets Renji because she thinks the relationship is more advanced than it actually is. Renji, being shy, reacts poorly to this, and Chihiro sometimes interprets it as rejection.

Chihiro has anterograde amnesia - the inability to persist new memories due to the accident that damaged her hippocampus, which is the part of the brain that organizes short term memories into long term memories. The defect is permanent and her memory will never be restored. She wears a paper eyepatch because after the accident, when the doctors tried to fit her with a glass eye, she would wake up and panic and rip it out of her eye socket. (A paper eyepatch is easier to replace every day.)

Chihiro in her memory prison

Chihiro knows that she is trapped by a 12 year chain beyond which she can go only 13 hours. This is her mental prison. This is shown metaphorically in Memories as an illuminated circle of glass that represents her maximum temporal reach, beyond which she cannot go.

In the final episode of Memories, Chihiro has an epiphany. She realizes that she can persist her feelings for Renji by thinking about him every day. As long as she thinks about him within the 13 hour window, she can roll it forward, and thus she can remember him indefinitely. With this knowledge she breaks her chains and frees herself. She reconciles with Renji, and they become a couple.

* Note: In Japan, the term 'younger twin sister' is not an oxymoron. Identical twins are distinguished between 'younger' and 'older' siblings, even if they are born only a minute apart.